About downfloats and upfloats

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David Sedgwick
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Re: About downfloats and upfloats

Post by David Sedgwick » Sun Sep 05, 2021 3:18 pm

Ian Thompson wrote:
Sun Sep 05, 2021 10:19 am
Roger de Coverly wrote:
Sun Sep 05, 2021 9:53 am
The Isle of Man Open had a novel idea of adding interest to the opening of the tournament and the first round by doing a random draw for some of the first round players. FIDE promptly banned the practice, presumably by disallowing Norms if the method was used.
Did they ban it or just point out that it violated the existing rule 1.42g for obtaining norms ("Tournaments that make changes to favour one or more players ... shall be excluded.") which it clearly did if you interpret the rule to mean the consequence of an action rather than its intent.
Werner Stubenvoll, the then Chairman of the FIDE Qualification Commission, gave permission for the method to be used in the Isle of Man in 2017. He declined a request for it to be allowed again in 2018.

I don't see the relevance of Rule 1.42g. That covers where you make changes to your presumed and announced method. The Isle of Man tournament said that they would conduct a random draw for the Round 1 pairings and that is what they did.

Incidentally, all of the Round 1 pairings were determined randomly, not just some of them.

Tim Spanton
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Re: About downfloats and upfloats

Post by Tim Spanton » Sun Sep 05, 2021 5:16 pm

Could you keep the identities of the players in an all-play-all secret and make them wear full face-covering masks, which would help preserve their anonymity AND protect against covid?

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Re: About downfloats and upfloats

Post by Ian Thompson » Sun Sep 05, 2021 5:33 pm

David Sedgwick wrote:
Sun Sep 05, 2021 3:18 pm
I don't see the relevance of Rule 1.42g. That covers where you make changes to your presumed and announced method. The Isle of Man tournament said that they would conduct a random draw for the Round 1 pairings and that is what they did.
I interpret "make changes" in "Tournaments that make changes to favour one or more players" to mean making changes to standard pairing rules, not making changes to previously announced pairing rules. If it didn't mean that you could have legal pairing rules that clearly favoured players seeking norms, e.g. anyone who is not an IM and has a current TPR exceeding 2450 will be paired against someone who is an IM or GM until they have played 3 such players.
David Sedgwick wrote:
Sun Sep 05, 2021 3:18 pm
Incidentally, all of the Round 1 pairings were determined randomly, not just some of them.
In that case, I agree Rule 1.42g was not violated because it didn't favour particular players if the entire draw was random. Roger said it was only some players.

Roger de Coverly
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Re: About downfloats and upfloats

Post by Roger de Coverly » Sun Sep 05, 2021 5:38 pm

David Sedgwick wrote:
Sun Sep 05, 2021 3:18 pm
Incidentally, all of the Round 1 pairings were determined randomly, not just some of them.
Perhaps I was remembering Gibraltar where I think they had some system of lottery for determining the opponents of the top ten seeds in the first round.

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Christopher Kreuzer
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Re: About downfloats and upfloats

Post by Christopher Kreuzer » Sun Sep 05, 2021 5:42 pm

Tim Spanton wrote:
Sun Sep 05, 2021 5:16 pm
Could you keep the identities of the players in an all-play-all secret and make them wear full face-covering masks, which would help preserve their anonymity AND protect against covid?
:lol: :lol:

I do think not knowing who you are playing against is against the FIDE rules.

Having said that, is it explicit in the rules that you have to know who you are playing? :?

David Sedgwick
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Re: About downfloats and upfloats

Post by David Sedgwick » Sun Sep 05, 2021 7:32 pm

Ian Thompson wrote:
Sun Sep 05, 2021 5:33 pm
I interpret "make changes" in "Tournaments that make changes to favour one or more players" to mean making changes to standard pairing rules, not making changes to previously announced pairing rules. If it didn't mean that you could have legal pairing rules that clearly favoured players seeking norms, e.g. anyone who is not an IM and has a current TPR exceeding 2450 will be paired against someone who is an IM or GM until they have played 3 such players.
There are two separate issues here.

If you wish to use a non-standard pairing method, you have to obtain the permission of the QC Chairman (now Nick Faulks) to use your method.

Then, having obtained any necessary permissions, you have to do what you have said you will do.

David Sedgwick
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Re: About downfloats and upfloats

Post by David Sedgwick » Sun Sep 05, 2021 7:35 pm

Roger de Coverly wrote:
Sun Sep 05, 2021 5:38 pm
David Sedgwick wrote:
Sun Sep 05, 2021 3:18 pm
Incidentally, all of the Round 1 pairings were determined randomly, not just some of them.
Perhaps I was remembering Gibraltar where I think they had some system of lottery for determining the opponents of the top ten seeds in the first round.
You are correct that that was the system in Gibraltar, although my recollection is that it involved fewer than ten pairings.

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Chris Goodall
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Re: About downfloats and upfloats

Post by Chris Goodall » Mon Sep 06, 2021 11:58 am

Alex McFarlane wrote:
Sun Sep 05, 2021 9:46 am
It does, but only fairly recently.

However, in theory, you can ask for your pairing system to be accepted. It was suggested that if the CAA method was computerised there was a fair chance that it would be. Unfortunately, the attempt to automate it failed to achieve the required level and was abandoned when the programmer lost interest.

FIDE from time to time does suggest that it might introduce the median of the score group as the player to get the bye.

There are a number of 'problems' with the FIDE system which the CAA one tried to avoid. The FIDE system (almost) always works down and ignores the actual rating. This means that if the pairing should be 5 v 23 but these players had already met, the FIDE system will look at 5 v 25 (assuming 24 is due white) and pair them rather than looking at 5 v 21 as well. The CAA system considers both options and chooses the one which minimises the rating difference. So even if 21 and 23 had the same rating the FIDE system would not swap the players. However, it is this that makes it so difficult to program.

If there are any programmers out there willing to give it a go ...
Okay! Do you have a preference as to programming language?

I have a feeling that the way to go with this is not to create a "smart" pairing algorithm that tries one pairing, calculates that it's undesirable, and tries another one. Instead, to start with a matrix of costs for every possible pairing, and have the algorithm solve for the lowest total cost. So 5 v 23 might have a cost of -100 for being the correct pairing according to the score groups, but +1,000,000 for having already been played. 5 v 25 might get -1 for being the next pairing "down" from the correct pairing, but +10 for a rating difference of 10, whereas 5 v 21 would get 0 on both position and rating difference, so 5 v 21 ends up as the cheapest pairing for now. If 5 v 21 causes the appearance of a +1,000,000 elsewhere in the pairings, the algorithm would eventually reject it and replace it with 5 v 25.

Then you can implement any change to the pairing rules by changing the cost matrix instead of changing the algorithm, which is miles easier. You can also ask the program "why is 5 not playing 21?" and it will tell you the cheapest set of pairings containing 5 v 21, sorted by cost. If there's a +1,000,000 in there, you have your answer as to why 5 is not playing 21.
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Chris Goodall
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Re: About downfloats and upfloats

Post by Chris Goodall » Mon Sep 06, 2021 12:32 pm

Ian Thompson wrote:
Sun Sep 05, 2021 1:01 pm
LawrenceCooper wrote:
Sun Sep 05, 2021 12:47 pm
Roger de Coverly wrote:
Sun Sep 05, 2021 12:31 pm


Surely in an all play all of 10, you would know the other 9 opponents, so with sufficient time have something prepared for each of them regardless of the order in which you played them.
Yes, it's hardly a foolproof plan and probably means some players may feel the need to prepare for every remaining opponent with both colours each night.
There's an exercise for someone with nothing better to do on a Sunday afternoon. If the organisers didn't disclose each player's pairing number, nor which round numbers were being played each round, how many rounds would it take for players to work out all the pairing numbers, and, from that, the colour they would get against each remaining opponent?
I will get back to you on that. I think it depends on which particular rounds get drawn. I also think that working out which colour you have against each remaining opponent may be easier than working out your number, at least for some combinations of rounds.
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Alex McFarlane
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Re: About downfloats and upfloats

Post by Alex McFarlane » Mon Sep 06, 2021 1:24 pm

Hi Chris,

I will email you re-pairing program.

On the APA, I came to the same conclusion. Another consideration which isn't stated is whether the board numbers are also scrambled. If not the player who is pin 10 will be known from round 2 without any real thought.